SAN FRANCISCO, CALIF.—Results of the randomized EVOLVE trial show that a bioabsorbable polymer everolimus-eluting stent was noninferior to a permanent polymer everolimus-eluting stent for the treatment of de novo atherosclerotic lesions. 

Ian T. Meredith, MBBS, PhD, of Monash Medical Centre Clayton, Melbourne, Australia, presented results of the EVOLVE trial, which was designed to compare the Synergy Everolimus-Eluting Coronary Stent System with the Promus Element stent. Researchers randomized 291 patients at 29 international sites to Synergy, full-dose (n = 94) or half-dose (n = 99), or Promus Element (n = 98; all Boston Scientific).

For the primary angiographic endpoint of in-stent late loss at 6 months, both dose formulations of the Synergy stent proved noninferior to Promus (figure).

In addition, 6-month in-stent minimal luminal diameter of the full- and half dose Synergy stents (2.41 mm and 2.45 mm) were larger than that of the Promus Element (2.29 mm; P = 0.08 for full-dose vs. Promus; P = 0.02 for half dose vs. Promus).

Both Synergy dose formulations showed rates of the primary clinical endpoint of target lesion failure (composite of target vessel-related death, MI and target lesion revascularization) at 30 days similar to that of the Promus Element (1.1%, 3.1% and 0%, respectively; P = 0.49 for full-dose vs. Promus and P =  0.25 for half-dose vs. Promus) The same was true at 6-month follow-up. In addition, at 6 months, no difference was seen among the stent arms for all-cause or cardiac death, MI, TLR or TVR. No cases of stent thrombosis were observed in any group.

Baseline and lesion characteristics of the three stent arms were similar, except for a smaller reference vessel diameter in the Promus Element group compared with the Synergy half-dose group (2.53 mm vs. 2.65 mm; P = 0.04).

The Synergy device is composed of a thin-strut platinum-chromium platform with a bioabsorbable PLGA polymer applied only to the abluminal surface. The polymer is completely absorbed within 4 months. The drug-release profile is similar to that of the Promus Element. The proposed advantage of a reduced polymer load is that it lessens short-term polymer exposure, thereby potentially reducing the chronic inflammation and impaired healing associated with durable polymer coatings.

Trial limitations

According to Meredith, limitations of the EVOLVE trial include enrolling patients with relatively simple lesions and follow-up of only 6 months. “But [the results] certainly prove the concept [of the efficacy of this bioabsorbable polymer stent],” he said. Meredith noted that additional research is needed to evaluate clinical event rates and the potential for reduction in the duration of dual antiplatelet therapy with this novel stent.

During a press conference, Roxana Mehran, MD, of Mount Sinai Medical Center, N.Y., said that designing a trial of sufficient size “to be able to show that something exciting and different is happening is going to be a challenge because the event rates are so low.”

Despite expressing concerns about the bioavailability of the drug, Ron Waksman, MD, of Washington Hospital Center, Washington, D.C., said that “if we have to choose between two stents, one with a durable polymer and one without a durable polymer, and the two behave the same [angiographically], I think we probably know the direction we should go.”

In response to a question about which Synergy drug dosage is more likely to move forward, Meredith said, “I suspect what will happen is that the clinical events will be followed over time and, if there is no disadvantage to the higher dose that might be more advantageous in more complex lesions.”